Rifling gun barrels



Oct. 22, 1957 A. SIMONS RIFLING GUN BARRELS Filed June 28. 1954 4 Sheets-Sheet 1 INVENTOR. ABRA HAN SI MONS ATTORNEYS Oct. 22, 1957 A. SIMONS 2,810,185

RIFLING GUN BARRELS Filed June 28. 1954 v 4 Sheets-Sheet 2 k v I w i 1 & I R W O Q N] N LL. Q Q:

w I W N a f E m w g N w INVENTOR.

' ABRAHAM SINDNS ATTORNEYS Oct. 22, 1957 A. SlMONs RIFLING GUN BARRELS' Filed June 28, 1954 4 Sheets-Sheet 3 FIG.5.

INVENTOR.

ABRAHAM SWIG/VS ATTORNEYS Oct. 22, 1957 A. SIMONS RIFLING GUN BARRELS 4 Sheets-Sheet 4 Filed June 28, 1954 FIG. 8.

INVENTOR. ABRAHAM SlMoA/s ATTORNEYS broachesj or ether 'm'etal removirig. tools. grooves;'are 'separatedfifrom reach other=byii1termediate GUNBARRELS Ahraham' simetissbnngpvaue N. Y., ass'ignor to Master Alloys, Ir'i., spring Valley, N. Y., a corporation ofNew York pp n-J ne 28.19 s sam 439,791 i is] tc'liis' r'l).

This invent-ion; relatesi particularly torrifling a gun ba'rrel. e

Theinyentiona includes; a new andfiimproved rifling method; a newr and improved rifling machine; a new and improved rihedi gun barrel; and a new-and' improved Heretofore, in; order to. rifle a gun. barrel; the general practice has been and is to drill: a longitudinal bore in -a metal blank. :This'drilled bore is substantially: cylindrical, withsurface irregularitiesvwhich result from the use of the drill.

atthe face oftherholie, by the use'of'a reamer. This operation slighly increases the diameter ofthedr'illed -bore, andj it; makes: the; drilled borexmore smooth and accurato he, he icalri'fling'; groovesare then:' formed: in' the race of there'amedt bore This is :done, by. cutting or otherwise 1 Q i g: thermaiteiiial of the "blank at the face of. the

bore, along spaced helical zones or areas; with thenseof faces of the originalireamed bore. T hese intermediate facesrlhave-r the .shapefwhich results; from the reaming.

These; intetmediate,,-f faees; arepgener'ally des'ignated as In\ the rhorezexpensiverifles, the rifling grooves*and i intermediateifaces-taie finished. by acutting or polishing operation; as hy-a: lapping tool, in. order tofm'ake the According-to this invention, the original blank inay he provided withthe usual initial longitudinal drilled hole,

which: is substantially cylindrical, with surface ii'rg- -ul'arities which resultfrom the operation of the drill.

The helical rifling grooves and the helical intermediate 'faces or lands of the rifled bore are thenformed ina single operation by pressure-shaping, without cutting awaynor removing the original material of the hollow blank in any other manner.

As one example, and for purposes of convenient ex- "planation, the outer longitudinalwall of the drilled blank 'inay" he cylindrical.

The pressure-shapirig which rifles the bore may not s'i1l' 'stai1t.ially change the original shape of the outer'longitudinal wall of the drilled blank, The change in the original shape of said outer longitudinal wall of the 'drilled blank maybe imperceptiblqor so slight as to be immaterial. The pressure-shapingincreases-the original density of the :metal' or alloy or othermaterial of the hollow blank.

increase indensityis a maximum' at the faces of the rifling grooves and atthe in'termediate faces lands 2,810,185 ---Patented: Oct. 22',- 1.957

of the. rifled bore; This increase in density diminishes towards the outer. longitudinal wall of the rifled blank.

- The increase in'de'nsity may result in some increase in hardness- Theincrease in density at and adjacent the faces of the rifling grooves and adjacent the intermediate faces or lands, is desirable, because. it increases the life of the rifled bore.

The pressure is exerted outwardly from the. face of the bd're towards the. outer longitudinal wall of the drilled blank. This outward'pressure is exerted upon helical zones or areas of the drilled bore, which correspond to the desired helical rifling grooves. Some outward pressure may beexerted upon the helical zones or areas which correspond tosaid intermediate faces or lands of the rifled bore; The. outward pressure thus reshapes the original drilled bore, in order to pressure-shape therifling igroovesandthe intermediate. walls or lands in a single operation, thus reducing thecost of rifling.

The'rifle'diblank has substantially the same volume as the original hollow blank, because the increase in original density produces only a slight change in the original volume.

The hollow blank may be at ordinary room tempera- "tureof 201 01- C. at the beginning ofthe rifling 25 The next op ration is: tofremove some of the material operation. Thepres'sure-sh'aping may be conducted slow- 51y, softh'at the resultant rise in the original temperature of the blank is insignificant.

The shaping pressure which rifles the bore, is not ap-- plied simultaneously along-the entire length of the bore. 30"

On thecontrary, the shaping pressure is always applied.

'o'nIya small-ffra'ctionof the entire axial length of the bore..

This pressure-applying section is shifted axially and. longitudinally from one end ofthe hereto the other'endi 'of'the bore.

As "part of a single operation, the original diameterof the original drilled bore is laterally enlarged 'directly preceding the application of the groove-forming, in the:

same single stroke of'the improved tool. Said original diameter of the original bore is thus enlarged'to provide:

lahihternal tapered fac'e of'the boreof the blank, directly' "in front of the application ofthe groove-formingfpres sure; so thatthe "rifling grooves are formed initially in. said internal tapered face. Said internal tapered face of the bore is also progressivelylongitudinally formed by pr'essure'which is longitudinal and which is outwardly directed towards the outer longitudinal wall of thedrilled. blank.

The method can be chines.

The invention is further disclosed in the annexed description and drawings, which illustrate a preferred embodiment of the improved machine and improved tool.

Fig. 1 is a longitudinal vertical section, partially in elevation. It shows'the parts of the machine and the blank at the beginning or" the rifling operation.

Fig. 2 is an enlarged elevation of the improved tool.

Fig. 3 is-an end-view of Fig. 2, at'the left side of Fig. 2.

Fig.- 4 is similar to fFig. l, showing the tool in termdiate the ends of the-original bore. 7

Fig 5 is a section on the line 5-5 of Fig. 4.

Fig." his a sectionon the line 6 6 of Fig. 4. V

Fig. 7 similar to Fig. l, showing the tool forced out of"the-blank,'at the end of the rifling operation.

is a section on the line 88of Fig. 7.

Fig. ,9 is a cross-section of the rifled bore which results from arifling operation according. to this invention.

The invention applies, if only. a single internal rifling practiced by many different ma-- F groove 'isfforrfiedalong the entire length of the face' of ""theboi'e of the'blank, or along only apart of said'hore.

In this example, four identical helical rifling grooves 20 of uniform pitch are formed. The rifled bore has four identical helical faces or lands 20a between said grooves 20.

The machine comprises a front shaft 1' which'is simultaneously moved longitudinally and turned around the axis of said shaft. The arrow 2 indicates the direction in which shaft 1 is turned in this example. The

shaft 1 may be turned in the reverse direction. The relation between the longitudinal movement of shaft 1 and its turning movement, is exactly the same as the uniform pitch of the rifling grooves 20.

A reduced and threaded extension 1a of shaft 1 is screwed into an internally threaded socket of a carrier 3 which has longitudinal inner and outer walls 3a and 3b of cylindrical shape.

These walls 3a and 3b have a common longitudinal axis, which is coincident with the common longitudinal axis of shaft 1, cylindrical rod R, axis 26 of tool T, the longitudinal axis of the original bore of the original hollow blank 9, and the cylindrical walls 8 and 8a. In this example, the original hollow blank 9 has an outer cylindrical Wall 9a, whose longitudinal axis is also coincident with said common longitudinal axis. The original bore 10 may be a drilled bore.

The carrier 3 is moved longitudinally and turned in exact unison with shaft 1.

The outer cylindrical wall 3b of carrier 3 fits closely and slidably and turnably in the longitudinal cylindrical wall Ga of a fixed guide G, Whose flange is fixed by members 6 to the fixed frame F of the machine.

The shaft 1 is made of metal of suitable strength, so that it can apply the necessary high pushing force to the cylindrical push-rod R, through the plug 4, which has an enlarged head 4a. This plug 4 is made of hard and rigid metal or alloy. Its shank is fixed rigidly in a longitudinal cylindrical bore of carrier 3, so that plug 4 is moved longitudinally and turned in exact unison with shaft 1 and carrier 3. The left or front end of push rod R, which is also made of hard and rigid metal or alloy, is rigidly fixed to plug 4, so that rod R is moved longitudinally and turned in exact unison with shaft 1, plug 4 and carrier 3.

In many cases, the cylindrical rod R must be long and of small diameter.

The caliber of a rifle is the diametral distance between two diametrically opposed lands or intermediate walls or faces 20a of the rifled bore. As one example, the length of the distance between the median points of two diametrically opposed intermediate faces or lands 20a may be 0.30 inch or approximately 7.50 millimeters, corresponding to 30 caliber. In such case, the length of the bore 10 of blank 9 may be 30 inches or approximately I 750 millimeters. In such case, the diameter of rod R must be substantially 7.50 millimeters, and its length in advance of plug 4 must exceed 750 millimeters, in order to force the tool T from its initial position of Fig. 1 to its final position of Fig. 7.

The longitudinal thrust which is exerted on rod R by shaft 1 through plug 4 may be as high as 80,000 pounds per square inch, or approximately 284 kilograms per square millimeter. In such case, the long and slender rod R, whose diameter is only 0.30 inch or 7.50 millimeters in this example, may be subjected to a longitudinal thrust as high as approximately 5600 pounds or approximately 12.320 kilograms. This high thrust will buckle the long free part or advance part of rod R out of straight shape, even if rod R is made of strong and hard material, such as the steel which is used to make a drill.

Hence the pins P are a very important part of the invention, because they prevent the rod R from buckling in advance of the holder 11, in which the original blank 9 is held fixed during the operation of the machine.

In this example, there are four longitudinal rows of the pins P, which are made of strong and hard material, such as the steel which is used to make a drill. In this example, the pins P are arranged in lateral sets, with four laterally alined and radially located pins P in each set. These longitudinal rows of pins P are equally angularly spaced by angles of as shown in Fig. 5 and Fig. 8.

Each pin P fits closely and slidably in a respective radial bore of the carrier 3, so that the pins P are moved longitudinally and are turned in exact unison with the carrier 3 and the rod R. Said pins P support rod R and keep rod R straight up to the front tapered and frustoconical wall 12 of the fixed holder 11 and the corresponding tapered wall 7 of the fixed guide G.

Each pin P is rounded at each end thereof. In advance of the wall 12 of holder 11, the inner end of each pin P closely abuts the cylindrical rod R, and the outer end of each pin P closely abuts the cylindrical wall Ga of the fixed guide G, thus closely supporting rod R and keeping it straight. The outer ends of pins P slide readily on the cylindrical wall Ga of the fixed guide G.

The longitudinal spacing between adjacent pins P is sufliciently small so that the pins P provide suflicient abutments for rod R in advance of the holder 11, to prevent rod R from bending out of accurate straight longitudinal shape. This longitudinal spacing depends upon the diameter and length of the free part of rod R. The longitudinal spacing of pins P may be greater in the case of a rod R of large diameter, and the pins P must be longitudinally close to each other if rod R is of small diameter. In many cases, it is sufficient if the longitudinal spacing of pins P is one inch or approximately 25 millimeters.

The rod R fits closely and slidably in the bore of the holder 11 which is provided at wall 12. The rod R also fits closely and slidably between the four intermediate walls or lands 20a, thus preventing the buckling of rod R in the bore of holder 11 at wall 12 and also in the final rifled bore.

Hence the rod R is kept straight in the rifled part of the bore 10, as the rifling progresses from one end of the bore 10 to the other end thereof.

The carrier 3 can be made of bronze or other bearing metal of low friction, so that the hard and strong steel pins P can slide easily in the radial bores of carrier 3. The hard and strong plug 4, which abuts or is very close to the end of the extension 111 of shaft 1, is provided to take up the longitudinal thrust and the turning force of the shaft 1, and to apply said thrust and turning force directly to rod R, thus eliminating excessive stress on carrier 3.

As above noted, the blank 9 is the original blank. This blank 9 is held rigidly in the fixed holder 11, so that blank 9 is not shifted longitudinally or turned in holder 11. This holder 11 has an inner longitudinal cylindrical Wall 1111. The blank 9 has an outer and longitudinal wall 9a, which is cylindrical in this example. The holder 11 has a longitudinal outer wall 8a of cylindrical shape. The inner cylindrical wall 3a of carrier 3 fits closely and slidably and turnably on the outer fixed cylindrical wall 8a of the fixed holder 11.

Adjacent the initial position of tool T which is shown in Fig. 1, the holder 11 has a vertical and planar wall 11b, against which the planar adjacent wall of blank 9 fits tightly. In this example, this part of holder 11 also has a short cylindrical wall, of smaller diameter than cylindrical Wall 11a. The adjacent part of the outer cylindrical wall 9a of blank 9 fits tightly in this short cylindrical Wall, so that blank 9 is always accurately centered at its front in the holder 11. The outer wall 9a of blank 9 may be of smaller diameter than inner wall 11a of holder 9, to provide a slight clearance between walls 9a and 11a. As above noted, there may be a small increase in the diameter of wall 9a of blank 9, as the result of the rifling pressure, and this slight clearance is provided for this purpose. In some cases, the entire inner wall 11a ,cone of which the frusto-conical wall 24 example, said internalangle, is 30.

' 'a clamping plug '14, whose shank has a cylindrical part which fits slidably and closely in the cylindrical wall 11a of holder 11. The shank of plug 14 also has a threaded part, and the bore of holder 11 has a corresponding threaded part, so that clamping plug 14 can be screwed tightly into holder 11 to exert sufficient longitudinal pressure upon blank 9, so that friction prevents the blank 9 1 from turning in holder 11.

The holdef 11 has another longitudinal cylindrical wall 110, which fits closely in a corresponding longitudinal'cylindrical wall of the fixed frame F of the machine. The holder 11 also has a flange or head 17. A clamping collar 16 and'clamping members 15, clamp the head 17 of holder 11 to frame F, so that holder 11 is held against turning relative to frame F.

The blank 9 is thus prevented from turning while the tool T 'is longitudinally shifted and turned around its axis 26.

The tool T has a rear cylindricalguide shank 23 Which fits closely and slidably'and turnably in the original cylin- 'drical bore of blank 9.

Tool T has a head 22. In this example, the tool T has four high walls or high faces 27, and four recesses 25. In this example, the four high faces 27 are parts of a cylinder whose axis is the longitudinal axis 26 of tool T, and whose diameter is the larger diameter 28a of Fig. 3. In this example, the four recesses 25 are identical, and

they have the same width and depth from end to end.

5 Each recess 25 is open at each end thereof.

Each recess 25 has two edges 28. The longitudinal shape ofeach recess 25 is the shape of a part of the helix of a respective intermediate face or land a of the .-rifled bore, so that each edge 28 has a part-helical shape.

That is, after the rifled bore has been formed by a tool T, said tool T can be moved through said rifled bore, while turning the tool T around its axis 26 in proper ratio to the longitudinal movement of tool T, corresponding to the pitch of the rifling grooves 20. In such case,

the high faces 27 of the tool T will interfit with and move through therifling grooves 29, and the recesses of the tool T will interfit with and move along and in contact with the intermediate faces or lands 20a of the rifled bore, while the tool T is moved completely through the rifled bore.

In this example, and without limitation thereto, the

shape of the high faces 27 of tool T,in each lateral plane which is perpendicular to axis 26 of tool T, is the shape of a part of a circle which is concentric with 'axis 26, and which has-the greater diameter 28a of Fig. -3; and

l the shape of the inner wall of each recess 25, in each said vertical lateral plane, is the shape of a part of a circle Which is concentric with said axis 26 and which has the smaller diameter 27a of Fig. 3. While the tool T is oper- Hence, in this example, referring to Fig. 9, each line -20a is part of a circle which is concentric with'the axis of the rifled bore,and which has the larger diameter 28a of Fig. 3; and each line of Fig. 9 which represents a face .or land 29a, is part of a circle which is concentric with the axis of the rifled bore, and which has the smaller diameter 27a of Fig. 3.

Intermediate the shank 23 and head 22, the tool T has a tapered wall 24, which has a frusto-conical shape. The

broken lines in Fig. 2 indicate the internal angle of the is a part. In this As above noted, the cylindrical guide shankj23 as tool T fits closely and slidably and turnablyinthe original bore 10.. The function of'f'the tapered wall-24 is to enlarge the front end of the original bore 1Q progressively as the 'tool T is moved in its simultaneous longitudinal-and turning movement through the original bore 10, so as to provide a tapered and frusto-conical enlargement 241 at i the front-part of the bore of blank 9 which has not yet been reshaped from its original cylindrical shape by wall V faces 27 of the tool T may fit closely and cylindricallbore of clamping plug 14.

is a clearance between head 22 'tudinal inner and cylindrical Wall The recesses 25 extend into a part of said frusto-conical wall 24, as shown in Fig. 2, and said recesses 25 also extend into the rounded junction between the head 22 and cylindrical shank 21 of tool T. Said shank 21 has a'fro'nt planar and vertical wall 21a, against which the rear vertical and planar wall of rod R abuts while the tool T is operated. 7 These vertical abutting walls may be smooth. I

' For COHVCIIICIICQfh longitudinal axis of the'machine is shown as beinghoriz'ontal but the invention is not limited to this position of said axis.

A cylindrical centering pin 18 fits closely and slidably in a cylindrical bore of clamping plug 14. This pin 18 has a cylindrical centering extension 19, which fits closely and slidably in the'rear part of original bore 10. This "centering pin: 18 remains in the centering position of *Fig. 1, until the guide shank 23 contacts with'the end of --centering n extension 19, at about the end of the rifling operation. The shank 23 then slides the centering pin 18 to itsfinal po'sition which is shown in Fig. 7, which evi- Ydence'sthe end of the rifling operation. The tool T is then located wholly in the bore of plug 14. The high slidably in the The operation is as follows: The walll'of'th e. original bore 10 is provided in the usual manner with a very thin lubricating film of metallic s copper, if a 'gun'barrel is to be rifled. This film of copper .is produced by precipitation or by electro-deposition in 40 the well-known manner.

This operation, like many other well-known operations which may precede or follow the rifling operation, is not described, because this invention relates to the rifling operation.

'The'rear guide shank 23 of tool T is inserted into the front end of the original bore 10, while the blank 9 and tool T are out of holder 11. The pre-assembled tool T and blank 9 are then inserted into the holder 11. There and the adjacent longiof the holder 11. The

clamping plug 14 is then screwed into its position of Fig.

'l,'thus clamping blank 9 in holder 11, so that blank 9 cannot turn' or shift in any manner.

V The centering pin 18 is inserted into the position of Fig. 1. V

At this time, the'shaft' 1, carrier 3 and rod R are approximately in the positions of Fig. 1. The rear-end 'part of rod R is located in the bore of holder 11. The longitudinal axis of bore 10 is coincident with axis 26 of tool T, and the common axis of shaft 1 and rod R.

The rear set of four'laterally alined rear pins P is close to the frusto-conical front wall 12 of holder 11. The shaft 1 is now forced longitudinally and rear- .wardly by any suitable mechanism, such as by a hydraulic press, and the shaft 1 is simultaneously turned around its axis by any suitable mechanism. The hydraulic press and the turning mechanism for turning shaft 1 are not shown, because they are well-known.

Shaft 1, rod R, carrier 3, its pins P, and tool T are moved longitudinally and simultaneously turned in exact unison, without any angular slip.

' Due to the construction of tool T, it is automatically turned around its axis 26 to produce rifling grooves 20 of the selected pitch, even if tool T is subjected only to a longitudinal thrust. The pitch of a rifling groove is long, so that tool T requires only a slight turning movement relative to its longitudinal movement.

no material is removed from the original blank.

The rod R also provides a turning force on tool T, due to the friction between the adjacent faces of rod R and shank 21. This frictional turning force on tool T may be substantial, due to the high longitudinal pressure between the rear vertical face of rod R and the front vertical face 21a of shank 21. For this reason, the relation of the turning movement of rod R to the longitudinal movement of rod R is exactly the same as the selected pitch of the rifling grooves 20.

The rod R and shank 21 may be fixed to each other by releasable fastening means, but this is not ordinarily necessary or even possible.

The tapered bore-enlargement 24! is thus progressively formed at the front end of the original bore 10. The axial length of bore-enlargement 24t is obviously much less than the axial length of bore 10. The diameter of shank 21 is less than the original diameter of bore 10.

As above noted, the rear ends of the recesses 25 of tool T extend into the tapered wall 24 of tool T, and said recesses .are optionally and preferably open at their respective ends, and said recesses 25 may be of equal width and of equal depth from end to end.

The unrecessed part of the tapered wall 24 subjects the metal or alloy or other material of blank 9 to considerable outward shaping pressure, in advance of the recesses 25. One of the functions of this unrecessed part of tapered wall 24 is to provide a smooth and tapered frustoconical shoulder 24t, thus eliminating any surface irregularities which may be caused by the prior drilling operation, if the original bore 10 is formed by a drill. The invention is not limited to drilling the original bore 10. Another function of the unrecessed part of tapered wall 24 is to subject the adjacent part of the material of blank 9 to permanent compression, so as permanently to increase the density of said adjacent part of said material.

The wall of blank 9, between its outer face 9a and the bore 10, is optionally sufliciently thick so that said outer face 9a retains its original shape, or substantially retains its original shape, during the entire rifling operation. The longitudinal movement and turning movement of tool T additionally permanently compresses the material of the blank at the high faces 27, thus forming and shaping the rifling grooves 20 by the pressure of said high faces 27, and permanently increasing the density of the material of the blank at the faces of said rifling grooves 20. The recesses 25 form and shape the lands 20a, and said recesses 25 also permanently compress the material of the blank adjacent said lands 20a, thus permanently increasing the density of the material at said faces 20a.

As above noted, said permanent increase in 'original density is a maximum at the inner wall of the rifled bore which is shown in Fig. 9, and said permanent increase in original density diminishes towards the outer face 9a of blank 9. Said permanent increase in original density is zero or negligible at the outer face 9a of the rifled barrel as the result of the rifling operation.

At the end of the pressure rifling operation, the weight of the rifled barrel is the same or substantially the same as the weight of the original blank, because little or In contrast, when the rifling is formed'by the old method, the weight of the rifled barrel is less than the weight of the original blank, the difference being the weight of the material which is removed to form the rifling grooves.

As the result of the one-step improved pressure-rifling operation, further finishing of'the rifled bore is optional, and usually unnecessary. a

At the beginning of the operation, the rod R cannot buckle in front of holder 11, because this is prevented by the supporting pins P. The example shows four longitudinal rows of pins P, 'but there may be more than four rows.

As the rod R is moved longitudinally rearwardly or to the right, as viewed in Fig. 1, each set of four pins 8 P slides in succession outwardly and radially away from the rod R. This is done by the tapered wall 12, which has the same taper as Wall 7. The pins P fit between tapered walls 12 and'7, and also between the cylindrical walls 8 and 8a. This fit need not be a tight fit.

In the rifled part of the bore, the high faces 27 fit closely in the rifting grooves 20, and there is a close fit between the recesses 25 and the intermediate walls or lands 20a.

As above noted, the rod R fits closely and slidably between the intermediate faces or lands 20a of the rifled here, so that the rod R is prevented from buckling within the rifled bore.

The rifling operation may be slow. Thus, it may be done in a period of eight to ten minutes, in rifling a steel barrel whose length is 750 millimeters, and whose rifled bore is 30 caliber.

At the end of the rifling operation, the tool T is located wholly in the clamping plug 14. This plug 14 is then unscrewed and removed from holder 11, thus removing the tool T from the machine.

The shaft 1 is then moved reversely or to the left, thus removing the rod R from the rifled bore. When the rod R is thus removed from the rifled bore, the movement of shaft 1 and rod R may be only longitudinal, or shaft 1 and rod R may be turned reversely to their original turning movement, with the same relation of turning movement to longitudinal movement.

The rifled blank or barrel can then be easily removed from the holder 11.

If the rifled barrel has a length of 30 inches or approximately 750 millimeters, and its rifled bore is to have 30 caliber, the following dimensions illustrate one working example:

Length of blank 9: 30 inches or approximately 750 millimeters.

Original diameter of bore 10: 0.280 inch or approximately 7.00 millimeters.

Diameter of guide shank 23: 0.278 inch or approximately 6.95 millimeters.

Larger diameter 28a: 0.306 inch or approximately 7.65 millimeters.

Smaller diameter 27a: 0.30 inch or about 7.50 millimeters. Hence the depth of each rifling groove 20 is 0.003 inch or approximately 0.075 millimeter in this example. This :depth may be increased or decreased, depending upon the selected design.

Diameter of wall 9a: 1.25 inches or approximately 31.25 millimeters. Hence the thickness of the wall of the original blank is 0.97 inch or approximately 24.25 millimeters.

These factors will vary, depending upon the original bore of the blank, the selected caliber, and the material of the blank, etc.

The above example applies generally to a steel gun barrel of the 30-30 type, of 30 caliber, whose length is 30 inches.

The rifting period is 8-10 minutes. The blank is at 20 C.30 C. prior to and during the rifling period.

Under the above mentioned conditions, the increase in the original diameter of the outer wall 9a of the original blank 9 is insignificant. Such increase is usually imperceptible. It may be in a range of 0.003 inch (approximately 0.075 millimeter) to 0.005 inch or approximately 0.125 millimeter.

In this example, as above noted, the original diameter of bore 10 is approximately 7.00 millimeters. This is permanently pressure-enlarged to approximately 7.65 millimeters at the rifling grooves 20, and to approximately 7.50 millimeters at the intermediate faces or lands 200.

As above noted, the depth of the rifling grooves 20 may be increased by increasing the larger diameter 28a.

The depth of the rifling grooves 20 depends upon the design and caliber of the rifle, so that such depth can be varied. While preferred, the invention is not limited to a pressure-shaped rifled barrel whose outer face has Elie tliriginal shape of original outer face 9a of the original The invention is not limited to the use of a blank which has an initial bore of cylindrical shape.

The scope of the invention includes every hollow body which has an internal face and one or more internal pressure-shaped helical grooves in said internal face, in which the weight of said hollow body, as the result of the groove-shaping operation, is substantially the same as the weight of the blank from which said hollow body was pressure-shaped.

The pressure-shaped rifling grooves 20 need not be identical, and the lands 20a need not be identical. Each high face 27 pressure-shapes a respective rifling groove 20 and each recess 25 pressure-shapes a respective land 20a. Hence it is within the scope of the invention to provide the tool T with different respective high faces 27 for pressure-shaping different rifling grooves 20, and with different respective land-shaping grooves 25 for pressure-shaping difierent lands 20a.

All the factors described herein depend upon the caliber of the rifled bore and the material of the blank. The twist or pitch of the riflin'g grooves also depends upon the caliber of the rifle, so that the drawings are wholly diagrammatic in showing the pitch.

Also, the invention is not limited to pushing the tool through the bore of the original blank. The tool T may be shifted longitudinally through the bore of the original blank while the tool is turned, in any manner and by any means. The tool T may be forced through the bore by liquid or grease under high pressure.

It is noted that the volume of the pressure-shaped body may be substantially equal to the volume of the original blank. The slightly lower volume of the pressure-shaped body may result solely from the increase in the original density of the original material. This is in sharp contrast with the volume of a rifled or grooved body which has been grooved by the use of a broach or other material-removing tool, in which the difference in volume between the grooved body and the original volume of the original body, is equal or substantially equal to the volume of the groove or grooves which are formed.

As above noted, the original blank is preferably coldworked as at C.30 C., during the pressure-shaping operation, so that if the original material of the original blank consists of a metal or alloy, the properties of said original material are not changed substantially by coldpressing at 20 C.30 C. or at other suitable low temperature, save for the cold-working effect.

The cold-pressing of a steel blank is defined as pressing below the critical thermal range of the respective steel. As is well-known, the cold-working of steel increases its yield strength and tensile strength and reduces its duetility. It is therefore desirable to limit these effects of cold-working to substantially the inner face of the pressure-shaped rifle bore of a steel barrel. The hot-working of steel usually takes place in a range of 1093 C. to 1426 C. The critical thermal range of steel depends upon its composition.

After the metal or alloy blank has been rifled, the rifled barrel may be subjected to any heat-treating operation or operations or other operations.

Likewise, the metal or alloy blank or other blank may be subjected to any operation prior to the rifling operation, so that the initial hollow blank can be reshaped by using a tool T of high-speed steel or other material which is harder than the metal or alloy or other material of the blank 9, in order to make pressure-reshaping possible, especially at the cold-working temperature of the respective metal or alloy.

I have disclosed a preferred embodiment of my invention, but numerous changes, omissions and additions and substitutions can be made without departing from its scope.

I claim:

1. A rifiing machine which has a frame and which includes a shaft which has a longitudinal axis, said shaft being longitudinally movable and being turnable around said axis, a straight cylindrical push-rod which extends in front of said shaft, said push-rod and shaft being coaxial, the rear end of said push-rod being rigidly connected to said shaft to move in unison with said shaft in the longitudinal and turning movements of said shaft, a hollow carrier, said push-rod being located in the interior of said hollow carrier, said carrier being rigidly connected to said shaft to move in unison with said shaft in the longitudinal and turning movement of said shaft, a fixed carrier-guide in which said carrier is located, said carrier being longitudinally movable and turnable relative to said carrier-guide, said carrier guide having radial sockets, slidable supporting pins located slidably in said sockets, said pins having inner ends which abut said push-rod, said pins having outer ends which abut said carrier-guide, said pins being provided in angularly disposed sets which hold said push-rod straight against buckling force, a hollow blank-holder located in front of said push-rod, said blank-holder having a front guide longitudinal bore at the end of said blank-holder which is proximate to said shaft, said cylindrical push-rod having substantially the same diameter as said guide-bore, said machine having displacing means for laterally shifting said pins away from said push-rod at the front end of said blank-holder, said blank-holder having a blankholding portion which is located rearwardly of said guide bore, said blank-holder having an intermediate hollow portion intermediate said guide-bore and said blank-holding portion, said intermediate guide portion being shaped to enclose a rifling tool which is movable longitudinally rearwardly by said push rod.

2. A machine according to claim 1, in which said displacing means consists of respective tapered walls of said blank-holder and said guide-carrier, said blank holder and the fixed frame of said machine have laterally adjacent cylindrical walls rearwardly of said tapered walls, the lateral distance between said cylindrical walls being at least equal to the lengths of said pins.

3. A machine which has a frame and which includes a shaft which has a longitudinal axis, said shaft being longitudinally forwardly movable and being also turnable about said axis, a straight push-rod which extends in front of said shaft, said push rod and shaft being co-axial, means connecting the rear end of said push rod rigidly to said push shaft to move the push rod in unison with said push shaft in the forwardly longitudinal and in the turning movements of said shaft, a hollow carrier, said push rod being located in the interior of said hollow carrier, said carrier being rigidly connected to said shaft to move in unison with said shaft in the longitudinal and turning movement of said shaft, a fixed carrier-guide in which said carrier is located, said carrier being longitudinally forwardly movable and being also turnable relative to said carrier guide, said carrier guide having radial sockets, slidable supporting pins located slidably in said sockets, said pins having inner ends which abut said push rod, said pins having outer ends which abut said carrier guide, said pins being adapted to hold said push rod straight against said buckling force, and means to move said pins radially outwardly away from said push rod during the forward stroke of said push rod.

References Cited in the file of this patent UNITED STATES PATENTS 1,275,028 Holter Aug. 6, 1918 1,311,584 Allgrunn July 29, 1919 1,329,444 Thompson Feb. 3, 1920 1,396,187 Garrow Nov. 8, 1921 1,819,257 Multhaupt Aug. 18, 1931 1,951,087 Dunn Mar. 13, 1934 2,383,356 Walker Aug. 21, 1945 2,641,822 Sampson June 16, 1953 

